A full-service Kinko's could print a HUGE map, with their poster- and banner-printing service. I think they're maximum width is 48"...

*searches*

Yep, 48" width max, and probably no length max. And, hell, if you're made of money, you could get it done on durable vinyl, which would support dry-erase markers (I suppose) for marking AoE effects, environmental damage, etc.